At the end of 1 year, the patients in the exercise group reported 20% to 30% less pain compared with a control group that was randomized to usual care. The benefits were consistent across subgroups, irrespective of age, disease stage, treatment regimen, or duration of aromatase inhibi­­-
t­or therapy.

“These results are a promising first step in developing clinical interventions that can improve aromatase inhibitor–associated joint pain and, in turn, adherence to aromatase inhibitor therapy, breast cancer survival, and quality of life,” said Dr Irwin.

Although they are a standard of care for hormone receptor–positive breast cancer, aromatase inhibitors cause arthralgias in a substantial proportion of patients, with the estimated frequency ranging as high as 50%. Known collectively as aromatase inhibitor musculoskeletal syndrome, the arthralgias cause some patients to stop taking their medication. The current clinical guidelines specify 5 years of treatment with an aromatase inhibitor after surgery for early breast cancer.

All study participants had been taking an aromatase inhibitor for at least 6 months, and all reported moderately painful arthralgias. Patients were randomized to a multimodality exercise regimen or to usual care, consisting primarily of education and advice about physical activity and monthly follow-up by telephone.

The exercise regimen consisted of twice-weekly supervised resistance and strength training and a weekly minimum of 150 minutes of at least moderate-intensity aerobic exercise (eg, brisk walking). Study participants randomized to the experimental arm also received free memberships to health clubs. The primary outcome was a change in pain scores, as assessed by the Brief Pain Inventory-Short Form.

Participants were well educated, overweight, and sedentary. The duration of aromatase inhibitor therapy at enrollment averaged 1.5 years.
When the trial ended, the data showed that the exercise group had significantly lower scores on all major pain parameters. Average worst pain decreased by 20% versus <1% in the control group (P = .017); average pain severity by 21% versus no change, respectively (P = .025); and pain-related interference with daily activities by 29% versus <1%, respectively (P = .005).

As a group, the patients randomized to the exercise program lost more weight and improved their exercise capacity compared with the control group. Moreover, pain relief occurred in a dose-response manner: patients who attended at least 80% of the supervised sessions had greater improvement in pain outcomes compared with participants who attended the sessions less frequently.

The trial’s primary objectives were related to the effect of physical activity on joint pain. Although a potential to improve adherence to aromatase inhibitor therapy was implied, that outcome was not specifically investigated, said Dr Irwin.